1. Field of the Invention
The present invention relates to the field of evaporative cooling, and, more particularly, to a dual usage two-stage indirect evaporative cooling system.
2. Description of the Related Art
A typical design for an evaporative cooler includes a water reservoir, a pump to circulate water from the water reservoir to evaporative pads, and an electric blower to draw outside air through the pads, cooling the air by evaporation. Such a design goes back at least to U.S. Pat. No. 838,602 to Zellweger, issued in 1906.
Although evaporative cooling systems are not as popular as they once were, they are still in wide usage in the desert Southwest, particularly in older homes and industrial buildings. It is quite common in these parts of the country, for example, for a warehouse or car repair facility to be cooled with an evaporative cooler.
The great virtue of the traditional evaporative cooler is the energy savings, but the biggest problem is that the cooled air tends to have a high humidity level, often 70-80%, which can feel uncomfortable. To remedy this problem, “two-stage” indirect evaporative coolers have been developed which provide cool air at a lower relative humidity. However, conventional two-stage indirect evaporative coolers do not meet the needs of many mixed use facilities where parts of the building (e.g., an office) require the dry air while other parts (e.g., a warehouse) do not.